Daiso Disposable Tea Bags
These High Quality, Disposable Tea Bags make it easy to place bonsai fertilizer on the soil. Placing your Sumo Cakes or other bonsai fertilizer in these bags allows the nutrients to seep into your soil as you water or when it rains. Filter bags hold the fertilizer and do not let the fertilizer clog your soil. Using tea bags for your bonsai fertilizer lets the fertilizer stay in place during watering or windy days.
When the fertilizer is used up, you simply pick up the tea bag and dispose of it.
You can read about the basics of fertilizing bonsai in this article. Learn the Basics About Bonsai Fertilizer